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<html>
    <head lang="en">
        <meta charset="UTF-8">
        <title></title>
        <style>
        .descendants *{
            display: block;
            border: 2px solid lightgrey;
            color: lightgray;
            padding: 5px;
            margin:15px;
        }
        </style>
        <script src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js">
        </script>
        
        <script>
            $(document).ready(function(){
                $("div").children().css({
                   "color":"red","border":"2px solid red" 
                });
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        </script>
    </head>
    <body>

        <div class="descendants" style="width:500px;">div当前元素
            <p>
                p 儿子元素
                <span>span 孙子元素</span>
            </p>
            <p>
                p 儿子元素
                <span>span 孙子元素</span>
            </p>

        </div>

    </body>
</html>